GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

B+

1

1

--

--

Left/Right Mirror Horizontal Motor Control

1

1

--

--

Left/Right Mirror Vertical Motor Control

1

1

--

--

Left/Right Mirror Motor Common Control

1

1

--

--

Switch Ground

--

1

--

--

1. Power mirror malfunction

Circuit/System Description

The outside rearview mirror switch supplies both voltage and ground to the outside rearview mirror motors. When the outside rearview mirror switch is being pressed the switch supplies the voltage and ground to the proper circuits to engage the proper mirror motor.

Reference Information

Schematic Reference

Outside Rearview Mirror Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Outside Mirror Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

  1. Ignition ON, with the mirror selector switch in the DRIVER position, command the mirrors UP, DOWN, LEFT, and RIGHT using the mirror directional switch. The driver mirror should move in the commanded direction.
  2. With the mirror selector switch in the PASSENGER position, command the mirrors UP, DOWN, LEFT, and RIGHT using the mirror directional switch. The passenger mirror should move in the commanded direction.

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the outside rearview mirror switch.
  2. Test for less than 10 ohms between the ground circuit terminal B and ground.
  3. If greater than the specified range, test the ground circuit for an open/high resistance.
  4. Verify that a test lamp illuminates between the B+ circuit terminal G and ground.
  5. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal replace the BCM.
  6. Connect the harness connector at the outside rearview mirror switch.
  7. Disconnect the harness connector at the appropriate outside rearview mirror.
  8. Connect a test lamp between the control circuit terminal C and the control circuit terminal B.
  9. Operate the vertical switch UP and DOWN. The test lamp should turn ON when commanding the UP and DOWN states.
  10. If the test lamp remains OFF during either of the commands, test for a short to voltage, short to ground or an open/high resistance on the control circuits. If the circuits test normal, replace the power mirror switch.
  11. Connect a test lamp between the control circuit terminal A and the control circuit terminal B.
  12. Operate the horizontal switch LEFT and RIGHT. The test lamp should turn ON when commanding the LEFT and RIGHT states.
  13. If the test lamp remains OFF during either of the commands, test for a short to voltage, short to ground or an open/high resistance on the control circuits. If the circuits test normal, replace the power mirror switch.
  14. If all circuits test normal, test or replace the outside rearview mirror motor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Outside Rearview Mirror Motor Replacement
    •  Power Mirror Switch Replacement